API: add an endpoint to get the list of contributors of a project or a component

[Deuchnord]

Is your feature request related to a problem? If so, please describe.

As the maintainer of a project, I would like to be able to generate a page that lists the contributors of my project/component based on the data provided by Weblate.

Describe the solution you'd like

Providing an endpoint to the REST API that returns a list of all the contributors would help a lot.

Describe alternatives you've considered

The solution that I have found is to create a JSON report manually from the /projects/{slug}/#reports page, but this means that I need to manually regenerate this report regularly, which is not really ideal for big projects with a lot of activity.
Plus, the reports only return the list of contributors on a given period, but I would prefer listing all the contributors (even those who haven't been active since a lot of time)

[nijel]

Duplicate of #5459